Gas burner ignition and safety control system



April 17, 1951 J, OTTMAR 2,549,633

GAS BURNER IGNITION AND SAFETY CONTROL SYSTEM Filed Dec. 22, 1945 2Sheets-Sheet l M MM!!! J. OTTMAR April 17, 1951 GAS BURNER IGNITION ANDSAFETY CONTROL SYSTEM 2 She ets-Sheet 2 Filed Dec. 22, 1945 FIGS.

Patent ed Apr. 17,3951

GAS BURNER IGNITION AND SAFETY CONTROL SYSTEM Jerome Ottmar, Attleboro,Mass, assignor to Metals & Controls Corporation,

Attleboro,

Mass., a corporation of Massachusetts Application December 22, 1945,Serial No. 636,996

7 Claims.

This invention relates to gas burner control systems and moreparticularly to safety control systems for gas burners.

Among the various objects of the invention are the provision of gasburner control systems providing a time delay between pilot ignition andmain burner ignition; the provision of a control system which avoidschattering of the main fuel supply valve in case of flame failure; theprovision of a control system which automatically shuts off the flow ofgas upon fiame failure; the provision of a control system which uponflame failure recycles .to relight the flame; the provision of a controlsystem which affords multiple recycling; and the provision of a controlsystem of the type referred to which is sturdy, reliable and constructedof few parts. Other objects will be in part apparent and in part pointedout hereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

Fig. l is a diagram of a control system of the present invention;

gig. 2 is a diagram of an alternative system; an

Fig. 3 is a diagram of a further alternative system.

Similar reference characters indicate corresponding parts throughout theseveral views of the drawings.

Referring to Fig. l, a gas burner control of this invention is shown toinclude a main gas burner I. Flow of gas to the main burner is undercontrol of a solenoid valve 3 in a main burner gas supply line 5. Abranch line I is connected into supply line 5 ahead of valve 3 forsupplying gas to a pilot burner 9, the latter being located in positionto ignite the main burner l. Flow oi gas to the pilot burner 9 is undercontrol of a pilot valve H in branch line 1. An electrical igniter l3,of the conventional hot wire type, is positioned to ignite gas flowingfrom the pilot burner when energized.

The main burner valve 3 includes'a solenoid coil 4, which whenenergized, operates upon a plunger 23 to open the valve. The valve isbiased to closed position by a spring 29. Plunger 28 also controls 'asecondary switch llassociated with valve 3, a stem 30 on the plungeropening this switch in response to opening of the valve and closing theswitch upon closure of the valve.

The pilot burner valve H is controlled by a thermal relay, generallydesignated N3, of the type disclosed in Wilson Patent 2,203,558.Generally, the relay comprises a pair of snap-acting thermostatic discs[2 and I4 confined at their edges and centrally attached to a stem 16for actuating the valve. These discs are controlled by an electricalresistance heating element 2| so as to snap from one position ofcurvature to an opposite position of curvature. When heater 2] isdeenergized and the discs cool, they snap to a position wherein valve Il is closed. When heater 2| is energized and the discs are therebyheated, they snap to the opposite position and open the valve. p

The solenoid coil :3 is connected across the wires 2'! and 47 of a powersupply circuit M. This is done by means of a circuit includinga maincontrol switch 25 and the contacts of a thermal time-delay relay 3?, tobe described. As illustrated, one terminal of the coil is connected by aline 3! including the main control switch 25 to line 41. The otherterminal of the coil is connected by a line 33 to one of the terminalsfor contacts 35. The other terminal for con-, tacts 35 is connected by aline 39 to line 21 of the power supply circuit. The main control switch25 may be either manually or automatically controlled. The circuit issuch that when switch 25 and contacts 35 are closed, current flows frompower supply line 4'! through line 31, solenoid coil 4, line 33,contacts 35 and-line 3G to the other power supply line 2'! to energizethe solenoid 4 and open valve 3. This also opens switch I1. The switchH, the heater 2! and the hot wire igniter [3 are connected in serieswith one am other and across lines 3! and 21, being under primarycontrol of main control switch 25. As .illustrated, one terminal ofheater 2: is connected by a line 23 to line 3i between switch 25 andsole-, noid coil 4. The other terminal of the heater is connected to oneterminal of switch H by aline IS. A line l5 including the igniter I3 isconnected between the other terminal of switch it and power line 2?. Thecircuit is such that with switches 25 and it closed, current flows fromline 3! through line 23, heater 2!, line 59, switch l7, line and igniter13 to line 21.

The thermal time-delay relay 3?, like relay it,

is also of the type disclosed in Wilson Patent; 3,558. It comprises apair of snap-acting v thermostatic discs l2 and |4 confined at theiredges and centrally attached to a stem it for actuating the contacts 35.The discs are controlled by an electrical resistance heating element 45to snap from one position of curvature to an opposite position ofcurvature. The relay 3'! is so constructed that when heater 45 isdeenergized and the discs cool, they snap to a position wherein contacts35 are open. When heater 45 is energized, and the discs are therebyheated, they snap to the opposite position and close the contacts. Fig.1 illustrates the latter condition.

The heater 45 is connected in series with a flame-sensitive currentcontroller 4| in the power circuit M. As illustrated, line 47 of thepower circuit is connected to one terminal of the heater. The otherterminal of the heater is connected to one terminal of currentcontroller 4| by a line 43. Line 27 is connected to the other terminalof controller 4|. The flame-sensitive current controller 4| is of thetype which is normally substantially nonconductive but which becomesconductive when heated in the reducing atmosphere of a flame, revertingto its normal nonconductive condition when the flame is out. Such acurrent controller is fully disclosed in Hower Patent 2,106,249.Controller 4| is so positioned that both the pilot and main burnerflames will act upon it. Thus, when either pilot burner 9 or main burneris ignited, controller 4| will be heated in a reducing atmosphere tocause it to become conductive. When both pilot burner 9 and main burnerI are extinguished, controller 4| is non-conductive. Since heater 45will not be energized to close contacts 35 unless controller 4| isconductive, solenoid coil 4 will not be energized and valve 3 will notopen unless the pilot burner 9 is ignited at the initiation of a cycle.

Operation of the Fig. 1 control is as follows:

Assuming that main burner valve 3 is closed, that pilot alve II isclosed and main control switch 25 is open, switch I! will be closedsince valve 3 is closed and contacts 35 will be open with heater 45cold. To start the burner, switch 25 is closed. This closes a circuitthrough line 23 to heater 2| of pilot relay I8, and through line i9,switch ll, line I5, pilot igniter 3 and line 21 back to the supplycircuit. After a predetermined period of time (preferably about 5seconds), igniter l3 has become heated and heater 2| causes discs l2 andI4 of relay l8 to snap open pilot burner valve This lights the pilotburner and its flame plays on flame-sensitive current controller 4|which thereupon becomes conductive and permits current to pass throughit and energize heater 45 of time-delay relay 3?. After a period oftime, heater 45 causes discs |2 and M of relay 3! to snap to theiropposite position of curvature and close contacts 35. This closes acircuit through solenoid coil 4 which moves plunger 28 to its Fig. 1position to open main valve 3.

Gas flowing through valve 3 into the main burner I is ignited by thepilot flame and the flame from burner I then also plays uponflamesensitive current controller 4|. As alve 3 opens, switch I! isopened, thereby breaking the circuit to igniter I3 and to heater 2|.After a predetermined time thermostatic discs |2 and M of re ay I 8 cooland snap to their position of opposite curvature closing pilot valve II.This turns on the pilot but does not affect the conductivity offlame-sensitive current controller 4| as it is now heated by the mainburner flame.

To extinguish the main burner flame, switch is opened to break thecircuit through line 3|, solenoid 4, line 33, contacts and line 39 fromthe supply circuit M. This releases plunger 28, and spring 29 thereuponbiases valve 3 to cut oil. further flow of gas to main burner This alsocloses switch l1. As soon as flame-sensitive current controller 4|reverts to its non-conducting state, it breaks the circuit to heater oftimedelay relay 37. After a predetermined period of time thermostaticdiscs 12 and 4 in relay 3'! snap to their position of opposite curvatureopening contacts 35.

All the contacts are thus reset to the off condition described above bythe opening of switch 25 and the device is ready for recycling.

In case the main burner is blown out, flamesensitive current controller4| will revert to its non-conducting condition and will not pass currentto heater 45 of time-delay relay 3! which will subsequently opencontacts 35. This breaks the circuit to solenoid coil 4 permittingspring 29 to close valve 3. Closing valve 3 closes switch I? so that,since switch 25 is still closed, the control will recycle in an attemptto relight main burner I.

If hot-wire igniter |3 should rupture, causing a break in the circuit,heater 2| of pilot relay |8 will receive no current, pilot valve U willnot open and the cycle described will not occur.

Fig. 2 illustrates another embodiment of the invention. As in the Fig. 1embodiment, the gas burner control is shown to include a main gas burnerand a solenoid valve 3 in the main gas burner supply line 5. A branchline is again connected into the supply line 5 ahead of valve 3 forsupplying gas to a pilot burner 9 located in position to ignite the mainburner. Flow of gas to the pilot burner, however, is under control ofpilot valve MI in line 1, rather than under control of relay-operatedvalve With valve 4| open, pilot burner 9 is ignited in any desiredmanner.

The solenoid coil 4 of solenoid valve 3 is connected across power supplycircuit M under control of a thermal time-delay relay 38 like relay 31of Fig. 1. As illustrated, relay 38 comprises a pair of snap-actingthermostatic discs 2 and I4 attached to a stem It carrying a contactorbar 65. These discs are controlled by an electrical resistance heatingelement 45 to snap from one position of curvature wherein bar bridgescontacts 61 and 39 to anopposite position of curvature wherein thesecontacts are open. When heater 45 is deenergized and the discs cool,they snap to a position wherein the contacts are open, as illustrated inFig. 2. When heater 45 is energized and the discs are thereby heated,they snap to the opposite position and move bar 65 to bridge thecontacts. A line I41 connects one side of the power supply circuit M andcontact 61. A line |5| connects contact 69 and one terminal of solenoidcoil 4. The other terminal of coil 4 is connected by a line I53 to theother side of the power supply circuit.

The relay heater 45 is connected across the power supply circuit M inseries With the flamesensitive current controller 4|. As illustrated,heater 45 is in a line 45 connected between line l4! and one terminal ofcontroller 4|. A line I43 connects the other terminal of the controllerto the other side of the power supply circuit. The controller 4| in thisinstance is positioned to be acted upon only by the flame 0f the pilotburner.

The operation of the Fig. 2 control is as follows:

' Inltially,.valve I41 is closed and the. pilotburner 8 and main burnerI, are not ignited. Since the pilot burner is extinguished,flame-sensitive current controller II is non-conductive and heater 45,connected in series therewith, is deenergized. Discs I2 and I4 of relay38 are therefore, cool and in their Fig. 2 position, having moved bar'65 away from contacts 61 and 69. 1

To start the burner, valve MI is, opened and the pilot burner 9' ignitedin any suitable way. The controller M is thereupon acted upon by thepilot burner flame to become conductive. This completes a circuit fromone side of supply circuit M through line I4I, relay heater 45, lineI45, controller 4| and line. I43 to. the other side ofthe supplycircuit. Thus, heater 46 is energized.

After a predetermined interval, heater 45 heats discs I2 and I4 of relay38 until they snap .to their opposite position wherein bar 65 bridgescontacts 61 and 69. This closes a circuit from one side of supplycircuit M through line I41, contact 61', bar 65, contact 69, line I5I,solenoid coil 4 and line I53v to. the other side of the supply circuit.This opens valve 3, admitting gas to main burner I, which is ignited bypilot burner 9.

When the main burner I is to be extinguished, valve I41 is closed toturn off the pilot 9. Flamesensitive current controller 4i thereuponbecomes non-conductive and heater '45 is deener-. gized. After apredetermined interval, discs I2 and I4- cool position, movingbar 65away from [contacts 61 and 69.. This breaks the circuit through solenoidcoil 4, whereupon spring 29. closes valve 3,.- shut.- ting ofithe flowof gas to burner I.

Fig. 3; illustrates another and third embodiment of the inventionincluding a main gas burner I and a solenoid valve 3 in the main burnersupply line 5. A branch line I is again connected into supply line 5ahead of; valve 3 for supplying gas to pilot burner 9. The latter islocated in position. to ignite the main burner I. As in the Fig. 1 form,flow of gas to the pilot burner is under control of a relay-operatedpilot valve III corresponding to valve I I" of Fig. 1.

An electrical igniter I3 is provided, as in Fig. 1,, to ignite the pilotburner. The igniter is connected across the power supply circuit inseries with a switch III associated with the valve. As illustrated,discs I2 and I4 of a thermal relay MB for the valve are attached to astem 64 carrying a contactor bar I65 adapted toclose and open, contactsI61" and I 69 of, switch III. .Stem M. has. a kno 65 fa te m n a ua onthereof. The discs, are controlled byelectrical resistance. heatingelement z-I to snap from one position of curvature to an oppositeposition of curvature. When heater 211 is deenergized and the discscool, they snap to a position wherein valve III is closed, as in thecase of valve II in, Fig. 1. When heater ZI is energized and the discsare thereby heated, they snap to a position wherein valve HI is opened.When valve II I is closed; bar I65 is disengaged from contact v I61 and169 (Fig. 3-). When valve III is open, bar I65 bridges the contacts. Thevalve I I i is biased closed by a spring 'I-I. When the valve is open, acircuit is completed from one side of the power supply circuit M throughlines I5, II, contact Ifil, bar 165 contact I69, line I9, igniter l3 andline 8,-I to. the other side of the supply circuit.

The relay heater 2| isconnected across the power supply circuit M inseries with flame-sensitiye cur nt oo tr le iltthela ter ing so.

sufficiently to snap to their normal ting gas to pilot. burner 3.

positioned that both the 'm in rner and p lot ,minal'. of heater 2-I andone; terminal of cone troller 41:, the other terminal of controller 4|.being connected; by line '81 to the other side of the power supplycircuit.

The coil 4. of solenoid valve 3' is connected in series with controller4| and with a room thermostat As: illustrated, a line 91 connects theterminal of controller II to. which line is C011,! nected and oneterminal of the.- solenoid coil 4. The. other terminal. of this coil isconnected by a line. 89 including" thermostat I3, and its sta-. tionarycontact. 93 to the side of the Supply circuit; Mother than that to:which. l n 8 i nected. I

The operation of the Fig. 3' embodiment is 'asfollows;

Upon a. demand for heat, room thermostat, I3 closes. This does not.establish a circuit through solenoid coil. 4, since. flame-sensitivecurrent controller M is: not. being acted upon by a flame and isnon-conductive. If knob 63' is now prshed down and held for a. fewseconds, a circuit is completed from one side of supply circuit Mthrough lines I5 and Ti, contact I61, bar I65, contact I69, line 19,ig-niter I3 and line 8%- to the other side of the supply circuit. Valve-EII i also manually opened against the bias of spring II, admit- As soonas, igniter I3 heats su-fiiciently, it will ignite the pilot burner.

The flame of the pilot burnerthen acts upon controller 4 I; t0v cause itto become conductive. This completes a circuit from one side of supplycircuit M through. lines t5 and 83, heater 2|, line 85, controller lland line 81 to the. other side of the supply circuit. Simultaneously, acircuit is completed from one. side of supply circuit lVi through roomthermostat. 13, line 89, solenoid coil 4. of valve 3, line SH,controller 41 and line 81 to the other side of the supply circuit.Solenoid valve. 3 thereupon opens, permitting gas to flow to. burner Iwhere it is ignited by pilot 9.

As soon as controller 4i becomes conductive and closes the circuit whichincludes heater 2I, this heater takes over the holding of discs I2 andI4 in the position to which they were pushed against the resistance ofspring II. Knob 63 can therefore be released at this point.

If now room thermostat I3 is satisfied it moves away from its stationarycontact 93 and breaks the circuit through solenoid 4. This permitsspring 29 to close, valve 3; to shut on the, flow of gas to. burner I.Pilot 9, however, remains lighted so that. controller II remainsconducting and valve 3 will promptly reopen when room thermostat I3subsequently calls for heat.

If now the flames of both pilot 9 and burner I are extinguished,controller 4| will become nonconducting and the circuits throughsolenoid 4 and through heater 2| are each broken. This permits spring 29to close valve 3 immediately and after a predetermined time interval,discs the invention, the valve 3 does not open to admitees. o he. b rnunt l h fiame sensi ive c rrent controller 4| has become conductive dueto ignition of the pilot burner 9. In the event of flame failure,controller 4| becomes non-conductive and valve 3 closes to shut off theflow of gas to the main burner. Controller 4| is not merelyheat-sensitive, but become conductive only in response to flame, hencewill not become conductive because of residual heat in the absence ofignition of one or the other of main burner I or pilot burner 9.

Each embodiment of the invention also includes a thermal time-delayrelay for delaying the opening of the valve 3 for a substantial intervalafter initiation Of operation of the system. Thus, in Fig. 1, relay 3!does not close contacts 35 immediately upon closure of switch 25, butdelays closure of these contacts until controller 4| has becomeconductive and heater 45 has been energized long enough to heat discs l2and M to cause them to snap. In Fig. 2, relay 38 does not move bar 65 toclose contacts 51 and 69 immediatel upon ignition of the pilot burner,but delays closure of the contacts until controller 4| ha becomeconductive and heater 45 has been energized long enough to heat discs l2and I4 to cause them to snap. In Fig. 3, valve 3 does not openimmediately upon closure of room thermostat 13, but opens after theperiod of time required for controller 4| to become conductive. Thisperiod is in turn determined by the length of time it takes heater 2| ofthermal relay M8 to heat discs l2 and M sufiiciently to cause them tosnap to and remain in the position wherein bar I65 bridges contacts I61and N59. The provision for delayed action of the main burnervalve 3 ineach instance prevents chattering of the valve in the event of anycurrent leakage through controller 4|.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. A gas burner control system comprising a main gas burner and a pilotburner for igniting said main burner, a gas supply line for said mainburner, a main valve in said line, a gas supply line for said pilotburner, a pilot valve in said pilot supply line, a main control switch,a thermal time-delay relay including contacts and a heater which, whenenergized, closes said contacts after a time delay, electricallycontrolled means for operating said main valve connected in a circuit inseries with said ma n control switch and the contacts of said time-delayrelay, a flame-sensitive current controller positioned to be acted uponat least by the flame of the pilot burner, said controller beingnormally non-conductve but adapted to become conductive when acted uponby said flame, said heater being connected in a circuit in series withsaid controller whereby said heater is energized in response to ignitionof the pilot burner and closes said contacts after a time delay therebyto open said main valve, a thermal pilot relay for operating said pilotvalve, said pilot relay including a heater which when energized actuatesthe pilot relay to open the pilot valve, a secondary switch, said pilotrelay heater being connected in a circuit under control of said maincontrol switch in series with said 8. secondary switch, and meansfor'open'in'g'said secondary switch in response to opening of said mainvalve and for closing it in response to closure of said main valve.

2. A gas burner system as set forth in claim 1, further including anelectrical igniter for the pilot burner in series with the pilot relayheater and secondary switch.

3. A gas burner control system comprising a main gas burner and a pilotburner for igniting said main burner, a gas supply line for said mainburner, a main valve in said line, a gas supply line for said pilotburner, a pilot valve in said pilot supply line, a main control switch,a normally non-conductive flame-sensitive current controller, the latterbeing positioned to be acted upon at least by the flame of the pilotburner and adapted to become conductive when acted upon by the flame,electrically controlled means for operating said main valve connected ina circuit in series with said main control switch and said currentcontroller, a thermal time-delay relay controlling said pilot valvehaving a cold position whereinit closes said pilot valve and a hotposition wherein it holds said pilot valve open,

4. A burner control system as set forth in claim 3, further including apilot burner igniter con nected in a circuit in series with a set ofcontacts controlled by said pilot valve, said contacts being open whensaid pilot valve is closed, and closed when said pilot valve is open.

5. A gas burner control system comprising a main gas burner and a pilotburner for igniting said main burner, a gas supply line for said mainburner, a valve in said line, electrically controlled means for openingand closing said valve, a flame-sensitive current controller which isnormallv non-conductive but which becomes conductive when acted upon bya flame, said controller being po itioned to be acted upon by the flameof the pilot burner, a thermal time-delay re ay compris n normally openthermostatically controlled contacts and an electrical heater whichafter being energized for a time delay interval acts to hold saidcontacts closed, and a c rcuit system including said electricallyoperated means, current controller and relay with the heater of therelay and the current controller being connected in series in a circuitin the system so that the heater is energized whenever the controllerhas be n rendered conduct ve due to be ng acted upon by the flame of thepilot burner, and with the contacts of the relay connected in anothercircuit in the sy tem controlling the operation of the burner so thatthere is a time delay between initiat on of operation of the burner andopening of the valve.

6. A gas burner control system comprising a main gas burner and a pilotburner for igniting said main burner, a gas supply line for said mainburner, a valve in said line, electrically controlled means for openingand closing said valve, a flame-sensitive current controller which isnormally non-conductive but which becomes conductive when acted upon bya flame, said con i anaese troller being positioned to be actedupon bythe flame of the pilot burner, a thermal time-delay relay comprisingnormally open thermostatically controlled contacts I and an electricalheater which after being energized for a time delay interval acts tohold said contacts closed, said heater and current controller beingconnected in series in a circuit so that the heater is energizedwhenever the controller has been rendered conductive due to being actedupon by the flame of the pilot burner, said contacts and electricallycontrolled means being connected in series in a circuit with said meansbeing adapted to hold said valve open only upon closure of saidcontacts.

7 A gas burner control system comprisinga main gas burner and a pilotburner for igniting said main burner, 'a gas supply line for said mainburner, a valve in said line, electrically controlled means for openingand closing said valve, a flame sensitive current controller which isnormally non-conductive but which becomes conductive when acted. upon'aflame, said controller being positioned to be acted upon by the flame ofthe pilot burner, a thermal time-delay relay comprising contacts,snap-acting thermostatic means controlling said contacts, saidthermostatic means, when cold, holding said contacts open,

I and an electrical heater which after being energized for a time delayinterval heats said thermostatic means tocause it to snap to a positionwherein it holds said contacts closed, said heater and currentcontroller being connected in series in a circuit so that the heater isenergized whenever the controller has been rendered conductive due tobeing acted upon by the flame of the pilot burner, said contacts andelectrically controlled REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,249 Hower Jan. 25, 19382,200,908 Beggs May l4, 1940 2,275,279 Beam May 3, 1942

